verify adding columes should work well

weed-fs/src/pkg/admin/storage_test.go

@@ -11,7 +11,7 @@ func TestXYZ(t *testing.T) {
 	dn := topology.NewDataNode("server1")
 	dn.Ip = "localhost"
 	dn.Port = 8080
-	vid, _:= storage.NewVolumeId("5")
+	vid, _:= storage.NewVolumeId("6")
 	out := AllocateVolume(dn,vid,storage.Copy00)
 	log.Println(out)
 }

weed-fs/src/pkg/storage/store.go

@@ -3,6 +3,7 @@ package storage
 import (
 	"encoding/json"
 	"errors"
+	"io/ioutil"
 	"log"
 	"net/url"
 	"pkg/util"
@@ -22,6 +23,7 @@ func NewStore(port int, publicUrl, dirname string, volumeListString string) (s *
 	s = &Store{Port: port, PublicUrl: publicUrl, dir: dirname}
 	s.volumes = make(map[VolumeId]*Volume)
 
+	s.loadExistingVolumes()
 	s.AddVolume(volumeListString, "00")
 
 	log.Println("Store started on dir:", dirname, "with", len(s.volumes), "volumes", volumeListString)
@@ -63,6 +65,23 @@ func (s *Store) addVolume(vid VolumeId, replicationType ReplicationType) error {
 	s.volumes[vid] = NewVolume(s.dir, vid, replicationType)
 	return nil
 }
+func (s *Store) loadExistingVolumes() {
+	if dirs, err := ioutil.ReadDir(s.dir); err == nil {
+		for _, dir := range dirs {
+			name := dir.Name()
+			if !dir.IsDir() && strings.HasSuffix(name, ".dat") {
+				base := name[:len(name)-len(".dat")]
+				if vid, err := NewVolumeId(base); err == nil {
+					if s.volumes[vid] == nil {
+						v := NewVolume(s.dir, vid, CopyNil)
+						s.volumes[vid] = v
+						log.Println("In dir", s.dir, "reads volume = ", vid, ", replicationType =", v.replicaType)
+					}
+				}
+			}
+		}
+	}
+}
 func (s *Store) Status() *[]*VolumeInfo {
 	stats := new([]*VolumeInfo)
 	for k, v := range s.volumes {

weed-fs/src/pkg/storage/volume.go

@@ -34,7 +34,11 @@ func NewVolume(dirname string, id VolumeId, replicationType ReplicationType) (v
 	if e != nil {
 		log.Fatalf("New Volume [ERROR] %s\n", e)
 	}
+	if replicationType == CopyNil {
+		v.readSuperBlock()
+	} else {
 		v.maybeWriteSuperBlock()
+	}
 	indexFile, ie := os.OpenFile(path.Join(v.dir, fileName+".idx"), os.O_RDWR|os.O_CREATE, 0644)
 	if ie != nil {
 		log.Fatalf("Write Volume Index [ERROR] %s\n", ie)
@@ -58,10 +62,18 @@ func (v *Volume) maybeWriteSuperBlock() {
 	stat, _ := v.dataFile.Stat()
 	if stat.Size() == 0 {
 		header := make([]byte, SuperBlockSize)
-		header[0] = byte(v.replicaType)
+		header[0] = 1
+		header[1] = byte(v.replicaType)
 		v.dataFile.Write(header)
 	}
 }
+func (v *Volume) readSuperBlock() {
+	v.dataFile.Seek(0, 0)
+	header := make([]byte, SuperBlockSize)
+	if _, error := v.dataFile.Read(header); error == nil {
+		v.replicaType = ReplicationType(header[1])
+	}
+}
 
 func (v *Volume) write(n *Needle) uint32 {
 	v.accessLock.Lock()

weed-fs/src/pkg/storage/volume_info.go

@@ -16,6 +16,7 @@ const (
 	Copy11               = ReplicationType(11) // 3 copies, 2 on different racks and local data center, 1 on different data center
 	Copy20               = ReplicationType(20) // 3 copies, each on dffereint data center
 	LengthRelicationType = 5
+	CopyNil              = ReplicationType(255) // nil value
 )
 
 func NewReplicationType(t string) ReplicationType {